Research On Prevention And Control Technology Of Rock Burst In Fully Mechanized Caving Face Of Gaojiapu Coal Mine

The research for the hazards of the failure expansion of the roof fracture is very important for the prediction of the dynamic hazards in extremely steep coal seams.Revolving around the problems of energy evolution in roof rock failure,Research set fully mechanized caving face of B1+2 coal seam of+495m level in Jiangou colliery as research area.Tempo-spatial evolution mechanism of released energy with roof-crack process was revealed in the research area with hybrid methods including theoretical analysis,numerical calculation,physical model experiment and field monitoring,launching project of the energy evolution with roof-crack process under the overlying coal pillar,and the achievement will provide a scientific basis for site hazard prediction and prevention,the research results are as follows:Firstly,the theoretical analysis and numerical calculation of the energy evolution of the steep coal seam was completed.The value of released strain energy being stored in the roof is obviously greater than the others,Excavation disturbance increase the damage of rock and releasing velocity of the strain energy increase remarkably due to roof-crack process.Under the overlying coal pillar,the energy distribution of roof in the area of adjacent the working surface is mainly higher than others,and the energy distribution of roof in the area of adjacent the overlying coal pillar is also higher.With excavation of model,the characters of energy releasing at different positions is diverse,the maximum energy is released at the position of adjacent working surface.Secondly,tempo-spatial evolution of energy with roof-crack process was revealed in the physical model experiment.During the experiment,the acoustic emission signal and infrared heat change at the same time,the relevant results indicate that traits of AE parameters value compose both slow evolution and rapid evolution.Heat Abnormal Zone(HAZ)emerges from the infrared thermal images and all the images could present migration phenomenon of the HAZ.The migratory phenomenon of acoustic-heat indicators is a result by inhomogeneous release of the released energy with roof-crack process.Tempo-spatial migration of the released energy is divided into slow evolution and rapid evolution.Finally,the evolution of released energy with roof-crack process was revealed in the field monitoring.During the field monitoring,the relevant results indicate that traits of the acoustic emission signal and the micro seismic signal compose both slow evolution and rapid evolution.the rupture of highly concentrated phenomenon emerge from the evolution of the maximum height of the fracture,it is mainly distributed in the short distance from working face.To analyze the evolution of the energy and frequency and the maximum height of the fracture is of great necessity.The tempo-spatial migration of the released energy is divided into slow evolution and rapid evolution during roof-crack process in extremely steep coal seams,and the maximum energy is released at the position of adjacent working surface,and the roof fracturing causing instability results in dynamic hazards in the research area while the induced energy is in the rapid evolution.The research is a scientific evaluation on roof instability induced by crack fracturing is crucially important for the prevention and control of dynamic hazards,and the achievement will provide a scientific basis for site hazard prediction.